When a plant, such as a tree, a bush or a shrub, is harvested for transplanting, it is necessary and advisable to leave a certain amount of soil around a root system of the plant. This network of roots and the soil clinging to them is known as a root ball, no matter the shape. The root ball is necessary to provide protection, moisture and nutrients to the roots between the time the plant is harvested and the time the plant is replanted.
However, many countries in Europe, Asia, the Middle East and South America, as well as certain states within the United States (both between states and foreign countries), do not allow foreign soil to enter their borders for fear of contaminating the domestic soil with contaminants and spores, including foreign insects, microbes, bacteria and fungi. These governmental restrictions have hindered the shipment of plants between various countries because of the need for a root ball around the root system until the plant is replanted. To overcome these governmental restrictions, nurseries or resellers typically wash a plant's root system to remove the native soil and then replant the root system into a cleaned soil mixture that has been pre-approved by the various country's regulating authorities. Another common method is to wash off the native soil and then repack the root system with a dry or semi-dry filler, which often consists of saw dust, peat moss or other natural filler, in the hope that such packing will protect the root system while in transit.
These methods have various disadvantages. For example, peat moss, which is a soil by-product, may not be allowed under various applicable regulations. Further, the mixture is generally hand packed around the root system in preparation for shipping. However, hand packing results in the formation of air pockets throughout the root system, and those air pockets cause damage to and may kill the roots, particularly the finer roots that are critical to increasing the chance of survival of a plant after it is replanted. Further, this mixture lacks the structural integrity necessary to survive the rigors of shipping and handling. The saw dust and peat moss do not adhere to each other or themselves well, and therefore do not form a cohesive root ball. The mixture crumbles easily, for example, from the handling and vibrations experienced during transportation of the plant.
To help alleviate many of the problems manifest in the hand packing method, some nurseries or resellers will wash the native soil from the root system and then plant the washed root system into a container filled with a pre-approved clean soil mixture. The nursery will then hold and nurture the plant for an extended period of time, thereby allowing the plant to “root out” in the clean soil mixture. The process of rooting out involves the plant growing new roots into the clean soil mixture. Depending on the plant, this process could take from six months to two years, which delays shipping and requires considerable resources or space and maintenance.